1. Technical Field
The present invention relates to a technology for recording an image with respect to a recording medium, particularly to a technology for controlling a tension applied to the recording medium.
2. Related Art
JP-A-2005-074773 discloses an image recording apparatus which records an image with respect to a transported sheet. Specifically, the sheet is transported by a rotation of two drive rollers on which the sheet is stretched. Then, a recording head facing the recording medium in between the drive rollers records the image with respect to the sheet transported from an upstream side to a downstream side of the transportation path. In addition, in JP-A-2005-074773, a sheet transportation speed by the upstream side drive roller is set to be faster than a sheet transportation speed of the downstream side drive roller. As a result, the sheet is pulled to the downstream side drive roller and the tension is applied to the sheet.
Furthermore, JP-A-04-094357 discloses a reeling and feeding apparatus which applies the tension to the transported sheet by a different method from the method disclosed in JP-A-2005-074773. In the reeling and feeding apparatus, both ends of the sheet is wound around a reel shaft and a roll shaft, the sheet is transported from the reel shaft to the roll shaft by rotations of the reel shaft and the roll shaft. Then, the tension is applied to the sheet by controlling a torque of the reel shaft. Particularly, in JP-A-04-094357, the tension to the sheet can be controlled by controlling the torque of the reel shaft based on a detection result of the tension to the sheet.
Incidentally, as the image recording apparatus disclosed in JP-A-2005-074773, in a configuration where a tension is applied to a recording medium (a sheet) by providing a difference in transportation speed of two drive rollers, there occurs a slip between a downstream side of the drive roller and the recording medium and the recording medium is easily flapping up and down. When such a flap occurs in a process region where an image is recorded on the recording medium, the image cannot be properly recorded on the recording medium. Therefore, it is conceivable to apply the technology disclosed in JP-A-04-094357 to the image recording apparatus disclosed in JP-A-2005-074773. That is, by adjusting a torque of the drive roller based on a detection result of the tension of the recording medium in the process region, it is expected that the flapping is suppressed and the tension can be applied to the recording medium in the process region.
However, in the case where a combination of technologies in JP-A-2005-074773 and JP-A-04-094357 is attempted like this, there has been a possibility that the tension of the recording medium becomes unstable in the process region. That is, in a configuration where a torque control is performed with respect to the drive roller, tension fluctuations may be transmitted to each other between the two regions which interpose the drive roller. Accordingly, since the torque control is applied to the drive roller, the tension fluctuations of the recording medium that occurs in the reverse side of the drive roller to the process region is transmitted to the recording medium in the process region. In this case, the tension fluctuations with a high frequency that occurs in the reverse side of the drive roller is transmitted to the process region to disturb the tension control in the process region, thus the tension of the recording medium in the process region vibrates and becomes unstable, and consequently, there has been a possibility that the image recording on the recording medium cannot be properly performed.